1. Field of the Invention
The technical field of the present invention relates to a semiconductor device using an oxide semiconductor.
In this specification, the semiconductor device refers to all the devices that operate by utilizing semiconductor characteristics. In this specification, a transistor is included in a non-linear element, the non-linear element is a semiconductor device, and an electrooptic device, a semiconductor circuit, and an electronic appliance including the non-linear element are all included in semiconductor devices.
2. Description of the Related Art
Many of transistors included in display devices typified by flat panel displays (e.g., liquid crystal display devices and light-emitting display devices) include silicon semiconductors such as amorphous silicon or polycrystalline silicon and are formed over glass substrates.
Attention has been directed to a technique by which, instead of such silicon semiconductors, metal oxides exhibiting semiconductor characteristics are used for transistors. Note that in this specification, a metal oxide exhibiting semiconductor characteristics is referred to as an oxide semiconductor.
As the oxide semiconductor, a single-component metal oxide such as tungsten oxide, tin oxide, indium oxide, or zinc oxide and an In—Ga—Zn-based oxide semiconductor which is a homologous compound are given. Techniques by which a transistor formed using the metal oxide is applied to a switching element of a pixel in a display device or the like have been already disclosed in Patent Documents 1 and 2.
As a semiconductor device formed using a silicon semiconductor, there is a semiconductor device for high power application, such as a field-effect transistor including metal and an oxide insulating film (a metal-oxide silicon field-effect transistor: MOSFET), a junction field-effect transistor (JFET), and a Schottky barrier diode.
In particular, silicon carbide (SiC), which is a silicon-based semiconductor material, is used in a Schottky barrier diode having small reverse saturation current and excellent withstand voltage characteristics (see Patent Document 3).